[main] flashcomm_v1 optim in Qwen Dense Models (#2802)

### What this PR does / why we need it?
Flashcomm_v1 optim in Qwen Dense Models.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
CI passed with new added/existing test.

- vLLM version: v0.10.1.1
- vLLM main:
5e537f45b4

Co-authored-by: 1024daniel <xxltju324@gmail.com>

vllm_ascend/utils.py

@@ -493,6 +493,7 @@ def register_ascend_customop():
     from vllm_ascend.ops.activation import AscendQuickGELU, AscendSiluAndMul
     from vllm_ascend.ops.linear import (AscendColumnParallelLinear,
                                         AscendMergedColumnParallelLinear,
+                                        AscendQKVParallelLinear,
                                         AscendRowParallelLinear)
     from vllm_ascend.ops.rotary_embedding import (
         AscendDeepseekScalingRotaryEmbedding, AscendRotaryEmbedding)
@@ -510,6 +511,8 @@ def register_ascend_customop():
                           name="RowParallelLinear")
     CustomOp.register_oot(_decorated_op_cls=AscendMergedColumnParallelLinear,
                           name="MergedColumnParallelLinear")
+    CustomOp.register_oot(_decorated_op_cls=AscendQKVParallelLinear,
+                          name="QKVParallelLinear")
     CustomOp.register_oot(
         _decorated_op_cls=AscendDeepseekScalingRotaryEmbedding,
         name="DeepseekScalingRotaryEmbedding")
@@ -572,3 +575,7 @@ def mlp_tp_enable() -> bool:
 
 def matmul_allreduce_enable() -> bool:
     return envs_ascend.VLLM_ASCEND_ENABLE_MATMUL_ALLREDUCE
+
+
+def dense_optim_enable() -> bool:
+    return envs_ascend.VLLM_ASCEND_ENABLE_DENSE_OPTIMIZE